Hi all…
My setup consist of a 2000 mah battery, a sparkfun power shield and a photon mounted on a weather shield from sparkfun too.
Everything works as expected, except if the battery gets drained… If it gets drained it never wakes up even after a full charge of the battery. It needs reflash ing or sometimes a reset press. Most of the time a reset press will do. Something that is simple, but on a remote difficult to perform 
In code I do disconnect from wifi and connect again to send events. If the battery power is below 50% and there’s no solar light, the device deep sleeps for an hour. If it comes back online and the power is bellow 30 percent it deep sleeps for 3 hours.
The device worked for 5 days straight and it did went to deep sleep as expected and waked up again as expected. The issue of not waking up happened on 3 straight cloudy days and the last report it made was with a battery at 30%. The device went to deep sleep and never waked up.
I am guessing the power went low on the battery and stayed low for a while, and since the solar cell does produce some power but not enough to to boot, I think the photon got powered with low voltage for a while, thus rendering the photon unusable unless reseted or sometimes reflash it. This time I am going to have to reflash it using the programming shield.
It would be desirable to have a circuit that some how shuts down all power on a certain voltage and then powers up when the tank is say… Half full… Thus not allowing the battery to under charge and damage the lipo, and also not allowing any damage to happen to the photon. Has anyone tried something like this? Does it seem viable? Or am I chasing ghosts?
Any ideas welcomed!